Device and method for determining a distance
The disclosure relates to an approximate determination of a distance between a wireless key which is assigned to a motor vehicle and a transceiver arrangement which is disposed in or on the motor vehicle. In the course of a ranging cycle, a first first path relating to a first threshold value and a second first path relating to a higher, second threshold value are calculated. Two distances are estimated on the basis of this dual first path calculation.
1. A distance determining device for determining a distance, wherein the device is configured to:
(a) define a first threshold value of a correlation between a first message to be sent and a second message to be received,
(b) define a second threshold value of a correlation between the first message to be sent and a third message to be received, wherein the second threshold value is greater than the first threshold value,
(c) send the first message via a transceiver arrangement disposed in or on a motor vehicle,
(d) receive the second message from an external first transmitter via the transceiver arrangement,
(e) receive the third message from an external second transmitter via the transceiver arrangement,
(f) determine a first correlation between the received second message and the sent first message, wherein the determined first correlation exceeds the first threshold value but not the second threshold value,
(g) determine a second correlation between the received third message and the sent first message, wherein the determined second correlation exceeds the second threshold value,
(h) calculate a first distance between the first external transmitter and the transceiver arrangement based on a travel time of the received second message, and
(i) calculate a second distance between the second external transmitter and the transceiver arrangement based on a travel time of the received third message.
2. The device as claimed in claim 1 , wherein the received second message is the message whose correlation exceeds the first threshold value for the first time.
3. The device as claimed in claim 1 , wherein the received third message is the message whose correlation exceeds the second threshold value for the first time.
4. The device as claimed in claim 1 , wherein the transceiver arrangement comprises at least three transceivers, and the device is further configured to:
carry out the functions (a) to (i) with respect to at least three of the transceivers,
calculate an estimated first position based on the first distances between the external first transmitter and the at least three transceivers, and
calculate an estimated second position based on the second distances between the external second transmitter and the at least three transceivers.
5. The device as claimed in claim 1 , wherein the device is configured to carry out distance bounding with the external transmitters and at least one transceiver selected from the at least three transceivers.
6. The device as claimed in claim 1 , wherein the device is configured to output the first distance and the second distance.
7. The device as claimed in claim 1 , wherein the device is configured to send the first message by ultra-wideband technology.
8. The device as claimed in claim 1 , wherein the first threshold value assumes a value of 3 sigma.
9. The device as claimed in claim 1 , wherein the second threshold value assumes a value of 6 sigma.
10. The device as claimed in claim 1 , wherein the device is configured to provide a preamble of the first message having a minimal data volume.
11. A motor vehicle comprising:
a device as claimed in claim 1 ,
the transceiver arrangement disposed in or on the motor vehicle, and
a wireless key assigned to the motor vehicle.
12. A method for determining a distance, the method comprising the steps of:
providing a motor vehicle, at in or on which a transceiver arrangement is disposed, and a wireless key assigned to the motor vehicle, and
determining an approximate distance between the transceiver arrangement and the wireless key by:
(a) defining a first threshold value of a correlation between a first message to be sent and a second message to be received,
(b) defining a second threshold value of a correlation between the first message to be sent and a third message to be received, wherein the second threshold value is greater than the first threshold value,
(c) sending the first message via the transceiver arrangement,
(d) receiving the second message from an external first transmitter via the transceiver arrangement,
(e) receiving the third message from an external second transmitter via the transceiver arrangement,
(f) determining a first correlation between the received second message and the sent first message, wherein the determined first correlation exceeds the first threshold value but not the second threshold value,
(g) determining a second correlation between the received third message and the sent first message, wherein the determined second correlation exceeds the second threshold value,
(h) calculating a first distance between the first external transmitter and the transceiver arrangement based on a travel time of the received second message, and
(i) calculating a second distance between the second external transmitter and the transceiver arrangement based on a travel time of the received third message.
13. A non-transitory computer usable medium having a computer readable program code embodied therein, the computer readable program code adapted to be executed on a processor to implement a method of determining a distance as claimed in claim 12 .